brainwagon

Readers might recall that I’ve been interested in small solar energy projects. In the past, I’ve played with a 25w solar panel, a Chinese PWM solar charge controller and a 7Ah battery, and I used it as the power source for a WSPR radio beacon that I ran for a few months in my back yard.

You can read about my fun with that here.

But last month I got more interested in using very tiny solar cells to harvest power and power very small applications, like powering garden lights or maybe running very small microcontrollers in low energy applications. So, I ordered 10 small 5v, 60ma solar cells from Banggood for about $1 each.

https://usa-m.banggood.com/10pcs-5V-60mA-Micro-Solar-Panel-for-Solar-Power-Mini-Solar-Cells-DIY-Electric-Toy-Materials-p-1377649.html

They arrived yesterday. I was feeling kind of bored this morning, so I soldered some clips on one of them, and then went outside with my snazzy Sparkfun multimeter that I got as swag from the Hackaday Superconference and tried aiming it at the sun to see what I got. Mind you, it was only 9:00AM, and we are still in January so the sun isn’t particularly bright, although it was clear.

And the results were pretty good for voltage:

But less so for current. I only got about 36 milliamps instead of the specified 60ma. But again, middle of winter, early morning, not too bad.

I also decided to see what kind of voltage and current I could get if I oriented the cell unoptimally, roughly straight up.

The result was about 5.63v at just 12ma, which is perhaps better than I might have expected.

All in all, I’m fairly pleased (although I haven’t tested them all). I suspect I could have gotten similar performance by looting $1 garden lights from Dollar Tree, but I think they will still be useful and will find their way into an experiment later on. I also ordered some QX5252F chips from ebay which should arrive “any day now”. These are popular in homebrew (and commercial) solar garden light circuits. It will be fun to play with them.

Stay tuned for more experiments.